1. Field of the Invention
The present invention relates to a computer program product, system, and method for establishing a point-in-time copy relationship between source logical addresses and target logical addresses.
2. Description of the Related Art
In a storage environment, volumes may be copied to other volumes to provide redundant copies of data or to store data as of a point-in-time. Snapshot is a common industry term denoting the ability to create a point-in-time (PiT) copy of all the data. Typically, snapshot creation is done instantly and the data is copied only when modified, referred to as a copy-on-write, in order to preserve the data as of the point-in-time the snapshot was created. Further, a background copy operation may be specified to copy the source data in the background to the target site to provide a redundant copy of the source data. A snapshot or PiT copy may be created using PiT copy techniques, such as IBM FlashCopy® (FlashCopy is a registered trademark of International Business Machines, Corp. or “IBM”).
To establish a PiT copy relationship between source data and target data, the IBM Data Facility Storage Management Subsystem (DFSMS) available with the IBM z/OS® operating system provides a FlashCopy establish (FCESTABL) command that allows the user to specify a source volume to copy to a target volume. The user may specify to only copy data in the source volume that is updated or to perform a background copy of the source volume to the target volume. (z/OS is a registered trademark of IBM in the United States and other countries).
The FCESTABL command also allows the user to specify a list of extents for the PiT copy, which comprises contiguous tracks that are less than all of the source volume and the target volume. The extents specified in the FCESTABL command indicate the first and last tracks on the source and target devices, which may be specified in cylinder and head number.
There is a need in the art for improved techniques for establishing a PiT copy relationship.